Most conventions have cosplay contests and it's cool to see who has the best costume. At a lot of the conventions you have to make your costume or have it made, it can't be mass produced off the internet. Even my boots are specially made for me, it's so awesome. everything is so elaborate and trying to prove you can turn cloth into a kick ass costume that everyone likes is awesome.
"The wound lies deep, like the ocean floor. The sin is red, growing paler in death."

Cosplaying is a great way to express your feelings for a particular character by roleplaying. Dedicated people who make their own outfits can also share tips, which builds a community. So basically it is an expensive hobby or just a wacky way to have fun.